How to Repair the Optiquest Q9b Monitor

How to Repair the Optiquest Q9b 19” Computer Monitor
The Optiquest Q9b 19” monitor is made by Viewsonic. Optiquest is their cheaper line.
Cheap may be an understatement. These monitors are poorly constructed and have a
habit of having the inverter burn out after 18-24 months of use. After research and
deconstructing a monitor, I have discovered that the inverter burn out is due to three
swollen capacitors. The capacitors used in this monitor can be attributed to what is
called the capacitor plague. These capacitors can be replaced in a fairly easy manner.
Items needed
3 470µF 35V 20% Radial-lead Electrolytic Capacitors
Phillips head screwdriver
A Small flathead screwdriver or a small plastic wedge
Soldering iron
Desoldering braid
Desoldering bulb or a solder sucker
Felt Tip marker
1. Remove the plastic shielding on the back of the monitor that covers the screwed
holding on the stand. This should come off easily by squeezing it, but sometimes
a flathead screwdriver is necessary to press the tabs to release the shielding.
2. Using the Phillips head screwdriver, remove the 8 screws holding the stand to
the monitor. The 2 screws in the lower corners are much longer than the other
screws. Remember these must go back in the same spot later. They are circled
3. Using the flathead screwdriver, or the plastic wedge, separate the outer plastic
casing of the monitor. There are inner tabs going around the entire monitor that
must be released. The screwdriver is generally more effective for releasing the
tabs, but a plastic wedge should be used if you are concerned about the
cosmetic look of the monitor.
4. Remove the back casing of the monitor. The casing will still be connected to the
monitor by a computer speaker connector since this model has built-in speakers.
Disconnect the cable and set aside the back casing.
5. The inner circuit boards of the monitor should be exposed. The one needing
repair is under the metal shielding. Remove the tape on the left side of the
6. Remove the 4 Phillips head screws holding the metal shielding in place.
7. Under the metal shielding is a yellow circuit board. This is the power inverter
board. This is the circuit board requiring repair. Using a Phillips head
screwdriver, remove the 4 screws holding the board in place. Three of screws are
shorter than the rest of the screws removed. The one screw closest to the AC
input has a washer.
8. On the left edge of the circuit board there are 4 sets of cables plugged in. Each
of these plugs has a small black dot on the side that is supposed to be facing up.
In order to remember which plug goes where, use a felt tipped marker to mark
the top of each socket.
9. Now, take note of the 3 capacitors that need to be replaced. They should look
swollen and bulging at the top where the metal is exposed.
10. On the underside of the board, take note of where the same capacitors are
soldered to the board.
11. Heat up the soldering iron and get the fresh solder ready. Once the soldering
iron is hot, apply some new solder to the old solder holding on the capacitor and
mix the new and old solder. This needs to be done to remove the old solder
because the old solder will not melt properly. Keep the soldering iron on the old
solder so it remains melted. When the solder is mixed and melted, use a
desoldering bulb or a solder sucker to remove the old solder. Use copper
desoldering braid as well to clean up any remaining solder. Try not to hit the
circuit board with the soldering iron as it can burn and damage the board.
12. When the majority of the old solder is removed from the capacitor, turn the
board so you can work on both sides the board at the same time. Take the
capacitor in one hand and continue applying heat to the solder on the underside
of the board using the other hand. The capacitor will become loose one side,
and then the other. Sometimes it might take several tries to get the capacitor
loose. Also, the capacitor may become warm as direct heat is being applied to
the leads on the capacitor. After the capacitor is removed, make sure the hole in
the board is clean and not covered by solder so the new capacitor can be easily
13. Repeat step 12 to remove the other 2 capacitors.
14. Below is the type of capacitor needed. The only place in most locations that
have them on hand is RadioShack. However, the capacitors can also be
purchased online. They cost about $1.40 a piece, but if you buy in larger
quantities there is a discount.
15. Insert the new capacitor into the holes on the board. Take note that the negative
lead on the capacitor matches up with the shaded part of the circle on the circuit
16. Apply hot solder to the underside of the circuit board to hold in the new
capacitor. Once again, be careful to not touch and burn the circuit board with
the soldering iron as it could damage the board.
17. Repeat step 16 for the next 2 capacitors.
18. Using a wire cutter, snip the excess length on the capacitor leads. Be sure to not
pull on the leads as it could damage the capacitor.
19. Reattach the circuit board to the monitor using the screws removed earlier.
Make sure to properly line up the board so the one plug on the right side of the
board inserts into the other circuit board.
20. Plug the cables back into the circuit board as marked earlier with the marker.
Make sure the side of the plug with the dot is facing up.
21. Replace the metal shielding over the circuit board and screw it back in using the
screws from earlier. After screwing in the shielding, this would be a good time to
test the monitor to make sure it is working again. If it is not working properly,
the capacitors may not be in properly or damaged, or there may be something
more wrong with the unit.
22. Reattach the back casing of the monitor. Make sure to attach the speaker cable
again to the circuit board as shown below.
23. Close the monitor casing. Reattach the monitor stand. Remember that the two
longer screws go on lower corners of the mount. Replace the plastic shielding
over the screws when finished.
24. The monitor should now be repaired and working. Throw out any broken items
such as the old capacitors and solder.